The subject matter disclosed herein relates to methods for screening for an aptamer. Aptamers are small synthetic nucleic acid strands that specifically bind to a target molecule with high affinity. One conventional method of aptamer selection is known as SELEX (Systematic Evolution of Ligands by Exponential enrichment). SELEX allows the screening of oligonucleotides against a variety of target ligands via an iterative and evolutionary process of continuous enrichment to identify target-specific binders. A typical SELEX library is vastly heterogeneous with a large number of distinct nucleic acid molecules (approximately 1013 molecules). Each molecule folds into a unique secondary structure, which leads to a distinct geometrical shape. Depending on shape complementarity and non-covalent electrostatic or hydrophobic interactions, a few DNA sequences can specifically bind to the desired target. Subsequently, bound sequences are separated and amplified using Polymerase Chain Reaction (PCR) to generate an evolved library. The process is repeated until high-affinity binders are enriched, resulting in a homogeneous library with high-affinity nucleic acid aptamers against the target of interest. SELEX has resulted in generating a significant number of aptamers against targets ranging from small molecules to whole cells; however, translational applications have been limited. To increase the clinical practicality of aptamer selection, development of methods to identify aptamers that could specifically recognize predetermined antigens in their endogenous state with no prior- or post SELEX sample manipulations on receptor proteins is desirable.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.